This section is intended to provide a background to the various embodiments of the technology described in this disclosure. The description in this section may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and/or claims of this disclosure and is not admitted to be prior art by the mere inclusion in this section.
In the 3rd Generation Partnership Project (3GPP), Interference Cancellation (IC) has been widely discussed. In Rel-11, Cell-specific Reference Signal (CRS) Interference Cancellation (CRS-IC), Primary Synchronization Signal (PSS)/Secondary Synchronization Signal (SSS), Physical Broadcast Channel (PBCH) IC has been standardized for heterogeneous network and homogeneous network. In Rel-11, in order to enable CRS-IC, PSS/SSS, PBCH IC, eNodeB (eNB) needs to provide UE with certain assistance information, e.g., CRS ports, cell ID, and MBSFN configuration. UE utilizes such information to cancel interference on CRS, PSS/SSS, PBCH and the like. To enhance UE's performance, Physical Downlink Share Channel (PDSCH) and Physical Downlink Control CHannel (PDCCH)/enhance Physical Downlink Control CHannel (ePDCCH) IC are being under discussion in Rel-12.
For the current cooperation transmission, UE has no capability for PDSCH IC. Hence, all the current cooperation transmission schemes are trying to minimize the interference from the transmitter side. However, for advanced UE with interference capability, the traditional cooperation transmission scheme is not the optimized transmission scheme.
Regarding IC, especially PDSCH IC, the key issue is to enable the UE to estimate the interference properly with certain accuracy, so that after a cancellation of this estimated interference from the received signal, detection performance based on the new resulting signal of the cancellation may be improved. Hence, estimation of the interference has decisive role in this cancellation operation.
However, usually, a blind detection of the interference estimation is either infeasible due to the UE's limited capability or results in a low accuracy or robustness. To have a best tradeoff between the cost and performance, so-called network-assisted IC is necessary.
For network-assisted IC, different IC methods can be used. Two kinds of IC methods are extensively discussed. One is Symbol Level Interference Cancellation (SLIC), and the other is CodeWord level Interference Cancellation (CWIC). For SLIC, an interference signal is regenerated after demodulation and is further subtracted from the received signal. For CWIC, an interference signal is synthesized after channel decoding and is further subtracted from the received signal.
To facilitate IC at UE side, firstly, the network may timely provide the UE with information, such as reference signal pattern, reference signal sequence and so on, so that the UE can estimate channel status between any of interferers and the UE as long as these interferences are intended to be cancelled. Secondly, depending on the UE's capability, an interfering signal' structure such as modulation mode/feature (for instance, modulation order) may be needed to be known to the UE. The more information on this interference signal structure, the more efficiently for the UE to do IC.
In other words, network-assisted IC is preferably to provide information about the interferers, including:                any information aiding the UE to infer interfering channel status; and        interfering signal structure or features.        
Owing to the existing multiple transmission (TX) modes, modulation levels, multiple antenna spatial beamforming, as well as dynamic scheduling, SU/MU TX style, shared-cell ID, and the like information about the interferes, an efficient solution of carrying out the network assistance is in demand.